1. Field of the Invention
The present invention relates to digital phase measurement, and, more particularly, to measurement of phase in signals with high dynamic range in both amplitude and phase, and with a high degree of modulation.
2. Background Art
Conventional phase meters have difficulty handling signals that have a high dynamic range in amplitude, and a high dynamic range in phase. Most phase meters work in the phase range between −π and +π, or, more commonly, in the range between
            -              π        2              ⁢                  ⁢    and    +            π      2        .  For most conventional phase meters, a phase in the hundreds of π, or millions of π, presents an insurmountable problem.
Another problem afflicting conventional phase meters is the dynamic range of the amplitude of the signal. For example, many conventional phase meters can handle a signal between, e.g., 0.5 volts and 5 volts. However, a signal that ranges between a few microvolts and a few volts (in other words, ranges over 40 dB in amplitude) is very difficult for conventional phase meters to handle accurately. Yet another problem is the change in the sign of the input signal, which often triggers “glitches” in conventional phase meter output.
Accordingly, there is a need in the art for a way to accurately measure phase of an input signal that has a high dynamic range (on the order of 40–50 dB) in amplitude with a high degree of modulation (for example, on the order of 50%), as well as optionally a high resolution in phase (for example, on the order of 2π·10−5 radian) and with no phase range limitation.